Mach reflection of a detonation wave over a concave double wedge

In this study, the Mach reflection of a detonation wave in 2H Subscript 2 2 ₂ + O Subscript 2 2 ₂ + 2Ar over a concave double wedge was experimentally investigated. Three Mach reflection configurations could be observed successively, namely, Mach reflection of a Chapman–Jouguet detonation over the first surface, Mach reflection of an overdriven detonation wave over the second surface, and Mach reflection after the interaction of two triple points. The experimental results indicated that the classical reactive theories based on the straight Mach stem assumption are unable to accurately predict the behaviours of the latter two Mach reflections. The asymptotic triple-point trajectory angle of the secondary Mach reflection, chi 2 χ 2 χ ₂ , is significantly smaller than the theoretical prediction. A curved model for the Mach stem m 1 m 1 m₁ is constructed, introducing a curved Mach stem near the triple point. The Mach stem has a concave curvature, implying a lower overdrive degree and a smaller incident angle, which consequently leads to a reduction in chi 2 χ 2 χ ₂ . Based on the curved Mach stem model, an equivalent wedge angle upper Phi Φ and an equivalent overdrive degree alpha overbar α ¯ α ̄ are introduced to predict the value of chi 2 χ 2 χ ₂ </jats:alterna